The present invention relates to a headrest and a method for manufacturing the headrest that is attached to a seat used as an automobile seat, a business seat, a consultation seat or a seat for house use. In particular, the present invention relates to a headrest that has a head angle adjusting mechanism and is manufactured by foaming and molding an expandable material together with a surface material and a method for manufacturing such a headrest.
A headrest of the art comprises a metallic or plastic stay frame as a skeleton of the headrest, a box like shaped surface material and a foamed cushion pad molded together with the surface material. Note that the surface material is seamed into a desirable box like shape, and a top part of the stay frame is capped with the surface material. Then, a liquid expandable material such as urethane is injected inside the box like shaped surface material and is foamed and molded together with the surface material. (see, for example, Japanese Patent Laying-Open No. Heisei 3(1991)-295617)
The surface material is manufactured by seaming several sheet materials into a box like shape corresponding to an outline of the headrest. Its margin is seamed as necessary to hide inside the box like shaped surface material to make the appearance of the surface material better. Thus, the seat materials are firstly seamed so as to appear in the inner side of the box like shaped surface material and provide an opening in a part corresponding to a bottom of the headrest. Then, the inner side of the surface material is disappeared by passing the surface material through the opening so as to appear as its outer side. Also, the top part of the stay frame is inserted in the surface material through this opening. The stay frame comprises the U-shaped top part and a pair of leg parts extending downward from both ends of this top part.
The foamed cushion pad is molded together with the surface material as follows. The top part of the stay frame is inserted in the box like surface material. Then, a liquid expandable material is injected in the surface material and is foamed. In Japanese Patent Laying Open No. Heisei 3(1992)-295617 described above, means for preventing a leakage of the liquid expandable material injected through the opening are described. The means comprise upper and lower plates having an opening for a liquid expandable material injecting nozzle and two holes for passing the leg parts of the stay frame, respectively. The leg parts of the stay frame pass through the holes of those plates so as to place those plates at a predetermined position corresponding to the bottom of the headrest. One plate is disposed in parallel to another plate, and a gap is provided between those plates. Note that the upper plate has a window as a fluid passage communicating with the gap between those plates. The opening of the surface material is inserted and freely held in the gap between those plates, and the upper plate having the fluid passage is disposed inside the surface material. Then, the liquid expandable material injecting nozzle is inserted in the inner space of the surface material through the openings coaxially provided in both plates and the liquid expandable material is injected and foamed therein. Note that the liquid expandable material injected passes through the fluid passage of the upper plate and is introduced between the upper plate and a circumferential portion of the opening of the surface material. This liquid expandable material is foamed and cured, and thereby, the opening of the surface material is completely closed.
Recently, a vehicle having a variety of functions has been developed. For example, in order to contain more passages or the like in a vehicle, a seat back is used as a part of a bed such that a rear seat is collapsed forward to create more space for containing more passages.
In such a vehicle, a rear seat must be tilted forward completely to make more space. However, if a non-tilt type headrest of the art as described above is attached to the rear seat, the rear seat touches on a seat back of a front seat when the rear seat is tilted. Thus, the rear seat cannot be tilted completely so that enough space cannot be created. In addition, in this case, if the headrest is detached from the rear seat, the rear seat can be tilted completely. However, additional space for putting the detached headrest will be required.
In view of those problems, it has been presented to attach a headrest having a head angle adjusting mechanism to a rear seat. This is because the rear seat can be tilted forward completely by tilting the headrest attached to the rear seat.
However, in a headrest incorporating such a head angle adjusting mechanism, the head angle adjusting mechanism is attached to the top part of the stay frame and, as well as a headrest of the art described above, the top part of the stay frame is capped with a surface material. Thus, if the liquid expandable material is injected inside the surface material and is foamed therein, a foamed cushion pad is formed so as to introduce into structural components of the head angle adjusting mechanism, and as a result, this pad hampers the functions of the head angle adjusting mechanism.
In addition, in order to recycle parts used for a vehicle, it is demanded to make components of a vehicle such as a headrest into pieces without taking much time and costing much labor. However, if a headrest has complex structures, it becomes difficult to make such a headrest into pieces, and thus, such a demand cannot be achieved.
Therefore, an object of the present invention is to provide a novel headrest and a headrest manufacturing method in which a foamed cushion pad is molded together with a surface material so as not to introduce a liquid expandable material into structural components of a head angle adjusting mechanism and it can be done to make the headrest into pieces without taking much time and costing much labor in order to recycle its components.
A headrest according to the present invention comprises:
(1) a stay frame assembly as a skeleton of the headrest comprising a base frame having at least one leg part extending downward, the leg part serving to attach the headrest to a seat; a head frame connected to a top part of the base frame so as to freely rotate the head frame backward and forward with respect to the base frame; and a head angle adjusting mechanism for adjusting an angle of the head frame with respect to the base frame;
(2) an inner cover comprising a box part for containing the head frame and the head angle adjusting mechanism; and a plate part connected to a bottom of the box part so as to leave a gap between the plate part and the bottom of the box part, at least one slot being formed in the plate part and this slot communicating with an inner space of the box part;
(3) a surface material having an inner space and an opening communicating with this inner space, an outline of the surface material corresponding to an outline of the headrest; and
(4) a foamed cushion pad molded together with the surface material such that a liquid expandable material is foamed in the inner space of the surface material so as to cover around the box part of the inner cover.
The head frame is covered with the inner cover such that the leg part of the base frame passes through the slot and extends outside the box part. The head angle adjusting mechanism of the stay frame is also covered with the box part so as to rotate the head frame backward and forward together with the inner cover.
Such a headrest can be manufactured as follows.
(Step 1)
The head frame is covered with the inner cover such that the leg part of the base frame passes through the slot and extends outside the box part, and the head angle adjusting mechanism of the stay frame is covered with the box part so as to rotate the head frame backward and forward together with the inner cover.
Note that the box part of the inner cover comprises two portions such as a first portion and a second portion, and the plate part described above is connected to the first portion so as to have a gap between the plate part and the bottom of the box part. That is, the head frame and the head angle adjusting mechanism are placed inside the first portion of the box part so as to pass the leg of the base frame, and then, the second portion is liquid-tightly attached to the first portion so as to form the box part. Thereby, the head frame and the head angle adjusting mechanism are covered with the inner cover.
Those portions can be liquid-tightly attached each other by fitting a tongue formed along an edge of one portion with a slot formed along an edge of another portion and then latching those portions. Then, the inside of the box part of the inner cover is formed, and the head frame of the stay frame assembly is fixed inside the inner cover so that the head frame is one body with the inner cover. The slot formed in the plate part is communicated with the inside of the inner cover and is formed so as to rotate the head frame backward and forward together with the inner cover with respect to the base frame. Preferably, a shape of the slot formed in the plate part is an elliptic shape extending from the front side to the rear side.
The first and second portions of the box part of the inner cover have first and second openings, respectively, so as to form a central opening passing through the box part from the front side to the rear side when one portion is attached to another portion as described above. The first and second openings are connected to each other by fitting a tongue formed on an edge of one opening with a slot formed on an edge of another opening and then latching those portions. A fluid passage is provided in a part of the bottom of the first portion of the box part so as to communicate with the gap between the plate part and the bottom of the first portion. Meanwhile, a hollow is formed below the second opening of the second portion, and the position and the size of the hollow correspond to the part of the bottom of the first portion having the fluid passage. Thus, when the first and second portions are connected to each other, the part of the bottom of the first portion is exposed through the hollow of the second portion. In addition, a liquid expandable material injecting nozzle inlet is provided in the first portion so as to vertically pass through both of the plate part and the part of the bottom of the first portion having the fluid passage. Also, a liquid expandable material injecting nozzle guide channel is provided just below the second opening of the second portion. Preferably, the fluid passage provided in the part of the bottom of the first portion is formed of a plurality of ribs, and a plurality of ribs are also provided vertically along an outer surface of a lower part of the first portion so as to enter the ribs into the gap between the plate part and the bottom of the first portion.
(Step 2)
The box part of the inner cover is inserted inside the surface material through the opening of the surface material, and a circumferential portion of the opening of the surface material is inserted in the gap between the plate part and the bottom of the inner cover. The circumferential portion of the opening is not tightly held in the gap. That is, this circumferential portion is freely held between the plate part and the bottom of the box part so as to allow the expansion of the whole of this surface material and not to produce a local tensile stress on the circumferential portion of the opening when a liquid expandable material is injected and foamed between the surface material and the box part.
(Step 3)
A liquid expandable material is injected between the surface material and the box part of the inner cover and is then foamed. Thereby, a foamed cushion pad molded together with the surface material is formed so as to cover around the box part of the inner cover. Meanwhile, the liquid expandable material flows between the bottom of the box part and the circumferential portion of the opening of the surface material freely held between the bottom of the box part and the plate part is foamed and cured so that the circumferential portion of the opening of the surface material is tightly held between the bottom of the box part and the plate part so as to completely close the opening of the surface material in the gap between the bottom of the box part and the plate part.
The liquid expandable material is injected between the surface material and the box part through the opening provided in the part of the bottom of the first portion of the box part. The liquid expandable material injected flows over the outer surface of the second portion of the box part, and a part of this liquid expandable material flows between the bottom of the inner cover and the circumferential portion of the opening of the surface material freely held between the bottom of the first portion of the box part and the plate part, through the fluid passage provided in the part of the bottom of the first portion of the box part. Meanwhile, a part of the liquid expandable material flows upward over the outer surface of the second portion of the box part, passes through the central opening passed through the box part so as to flow this liquid expandable material to an outer surface of the first portion of the box part and flows over the outer surface of the first portion. As described above, the ribs are preferably provided vertically along the lower surface of the first portion so as to enter the ribs into the gap between the bottom of the first portion and the plate part, and a part of this liquid expandable material is introduced over the outer surface of the first portion, flows between the bottom of the inner cover and the circumferential portion of the opening of the surface material freely held between the bottom of the first portion of the box part and the plate part, through the ribs. As described above, the liquid expandable material injected is supplied around the whole of the box part and is then foamed, and thereby, the foamed cushion pad molded together with the surface material is formed.